Good causes in Scotland risk losing out on millions of pounds of National Lottery funding if voters back independence, Alistair Darling will warn charities today.

The leader of the Better Together campaign will state that only one per cent of Lottery funding has been given to programmes outside the UK over the past decade.

In a speech to the Scottish Council for Voluntary Organisations (SCVO), which represents the charity sector, he will argue that good causes north of the Border only get the funding “because we are part of the UK”.

But the former Labour Chancellor will warn this situation would “fundamentally change” if there was a vote for separation in September this year.

Mr Darling will argue that the National Lottery is a good example of the “social union” whereby money raised elsewhere in the UK is used for the benefit of Scots.

The Scottish Government’s White Paper on independence promised the Lottery would continue to operate north of the Border after separation and Scotland would continue “to receive our fair share of funding”.

Camelot, which has the licence to run the National Lottery until 2023, has said the final decision “would be a matter for the respective governments”. This means Westminster would have to agree to the Lottery operating in an independent Scotland.

Speaking at the SCVO conference in Glasgow, Mr Darling will say: “As part of the UK we have more funds at our disposal to bring about the kind of change our communities need. Shutting ourselves off from what we know has worked makes no sense.

“Projects and groups in Scotland have received substantial funding from the National Lottery. It’s a cross border relationship that works, but only because we are part of the UK. Leaving the UK would fundamentally change that.”

Better Together pointed to a parliamentary answer showing that only 739 of the 226,000 National Lottery grants – representing one per cent of their total value – have been classified as “overseas” over the past decade.

They were defined as those made to projects located in “all countries outside the United Kingdom”.

A spokesman for the pro-separation Yes Scotland campaign said: “Mr Darling knows perfectly well that the enduring social union that exists in these islands is not dependent upon the decaying Westminster political union.

“Indeed, several charities operate successfully throughout the UK and Ireland such as the Salvation Army and the RNLI.”

Meanwhile, a new opinion poll published today found support for independence unchanged at the start of this year, with 29 per cent of Scots intending to vote ‘yes’, 42 per cent opposed and 29 per cent undecided.

The TNS survey showed the gap closed to only nine points among those certain to vote, with 35 per cent backing separation and 44 per cent against it.

However, it was conducted before the three main UK parties rejected Mr Salmond’s plan for a currency union and senior EU figures said it would be “difficult, if not impossible” for a separate Scotland to join.